Lecture 4 Experience and Induction WANG Huaping Philosophy Department, Shandong University

Contents Deduction and Induction 2 Problems 4 Experience and Empiricism 31 The Method of Three Tables 33

Consider the Following Questions  How do we know that a bachelor is not married?  How do we know that the sun rises at X- o’clock to-morrow? Differences?

Experience and Empiricism  Demonstrative science is based on deduction. The obvious objection to it from the modern point of view that there is little about the role of actual sensory experience in the acquisition of knowledge of how things work. If we want to know whether metals expand when heated we expect to go out and look at how metal actually behaves in various circumstances, rather than to try and deduce a conclusion from first principles.

Experience and Empiricism  To the modern mind, science is immediately associated with experiments and the gathering of data about what actually happens in various circumstances and hence with a school of thought in epistemology called empiricism.  Empiricists believe that knowledge can only be obtained through the use of the senses to find out about the world and not by the use of pure thought or reason; in other words, the way to arrive at justified beliefs about the world is to obtain evidence by making observations or gathering data.

Deduction and Induction  In deductive reasoning, conclusion is implicit in the premises. Thus, deduction is truth- preserving, that is, if you have an argument with true premises, then the conclusion will be true as well. Such an argument, we say it is valid. In other words, if an argument is valid then it is impossible for the premises all to be true and the conclusion false.  If a valid argument happens to have true premises it is said to be sound.

Deduction and Induction  So how to expand our knowledge?  Deduction seems unable to do so. The conclusion of a deductively valid argument cannot say more than is implicit in the premises. In a sense, such arguments do not expand our knowledge because their conclusions merely reveal what their premises already state, although where the argument is complex we may find the conclusion surprising just because we hadn’t noticed that it was already implicit in the premises.

Deduction and Induction  An effective way is to observe. By observation, we learn from experience that things are such and such. And thus we gain knowledge through experience. Such knowledge constitutes empirical science.  The logic of empirical science is not the same as demonstrative science!  Bacon proposed his ‘inductive logic’ to replace Aristotelian methods.

Deduction and Induction  Inductive reasoning, or induction, is the name given to various kinds of deductively invalid but allegedly good arguments. Not all invalid arguments are intuitively bad arguments. For example: Tom claims to be a philosopher. I have no reason to believe he is lying. Therefore Tom is a philosopher. We do use such reasoning in everyday life.

Deduction and Induction  After Bacon, induction is used to reasoning leading in or drawing off a general fact from a number of instances, or summing up the results of observations and experiments.  Induction is a form of ampliative reasoning. Ampliative reasoning is one that adds to that which is already known. The other form of ampliative reasoning is eduction, which moves from premises mentioning particulars to a conclusion mentioning another particular.

 Inductive arguments are evaluated as more or less strong, more or less cogent.  Strength is the inductive analogue of validity, for it concerns the inferential connections between premises and conclusion (though whereas strength comes in degrees, validity does not)  Cogency is the inductive analogue of soundness (a cogent argument is a strong argument with true premises) Deduction and Induction

In ordinary contexts, we say “good” arguments. In logical contexts, we must also show that our kind of argument passes the two essential tests of any argument. “Good” Argument = Truth + Good Reasoning Sound Arguments Truth + Certainty (all or nothing) Cogent Arguments Truth + Probability (degrees of acceptability) Deduction and Induction

 Which of the following arguments is inductive argument? Watches exhibit order, function, and design. They also were all created by a creator. The universe, much like a watch, exhibits order, function, and design. So, the universe must have been created by a creator. All of the swans we have seen are white. All swans are white. The Inductive Method

 Which of the following inductive argument is strong? And which one is cogent? Every monkey I’ve seen so far has blue teeth. All monkeys have blue teeth. I always hang pictures on nails. Therefore: All pictures hang from nails. All of the swans we have seen are white. All swans are white. Deduction and Induction

Books on logic are divided into two parts: a part one, on deduction, in which fallacies are explained, and a part two, on induction, in which fallacies are committed. Morris Cohen Deduction and Induction

The Method of Three Tables   Induction is the name given to various kinds of deductively invalid but allegedly good arguments.   So what distinguishes bad invalid arguments from good ones, if indeed there are any of the latter?   Bacon has given an answer to this question that has two aspects: a negative one and a positive one.   The negative aspect amounts to a way of avoiding falling into error which gets in the way of right inductive reasoning. Bacon called it the Idols of the Mind.

The Method of Three Tables (1) Idols of the Tribe The first are the Idols of the Tribe, which refers to the tendency of all human beings to perceive more order and regularity in nature than there is in reality, for example, the long-standing view mentioned above that all heavenly bodies move in perfect circles, and to see things in terms of our preconceptions and ignore what doesn’t fit in with them.

The Method of Three Tables (2) Idols of the Cave The Idols of the Cave are individual weaknesses in reasoning due to particular personalities and likes and dislikes; someone may, for example, be either conservative or radical in temperament and this may prejudice them in their view of some subject matter.

(3) The Idols of the Marketplace The Idols of the Marketplace are the confusions engendered by our received language and terminology, which may be inappropriate yet which condition our thinking; so, for example, we may be led into error by our using the same word for the metal lead and for that part of a pencil that makes a mark on paper. The Method of Three Tables

(4) Idols of the Theatre Finally, the Idols of the Theatre are the philosophical systems that incorporate mistaken methods, such as Aristotle’s, for acquiring knowledge. These systems resemble plays in so far as they render fictional worlds, which were never exposed to an experimental check or to a test by experience. The idols of the theatre thus have their origin in dogmatic philosophy or in wrong laws of demonstration The Method of Three Tables

  The positive aspect of Bacon’s answer to the question of induction begins with the making of observations that are free from the malign influence of the first three Idols. The idea is to reach the truth by gathering a mass of information about particular states of affairs and building from them step by step to reach a general conclusion. This process is what Bacon called the composition of a Natural and Experimental History. The Method of Three Tables

  Experiments are important because if we simply observe what happens around us we are limited in the data we can gather; when we perform an experiment we control the conditions of observation as far as is possible and manipulate the conditions of the experiment to see what happens in circumstances that may never happen otherwise. Experiments allow us to ask ‘what would happen if...?’. Bacon says that by carrying out experiments we are able to ‘torture nature for her secrets’. The Method of Three Tables

  Experiments are supposed to use instruments to record the results, so that the perception of the individual performing the experiment does not affect the way the outcome is reported to others. Bacon stressed the role of instruments to eliminate, as far as possible, the unreliable senses from scientific data gathering. In this way the scientific method of gathering data that will count as evidence for or against some view or other is supposed to ensure objectivity or impartiality. The Method of Three Tables

  Having gathered data, we must then put the data in tables of various kinds. This process is best illustrated with Bacon’s own example of the investigation of the phenomenon of heat. The first table to be drawn up is that of Essence and Presence, which consists of a list of all the things of which heat is a feature, for example, the Sun at noon, lava, fire, boiling liquid, things that have been vigorously rubbed and so on. The Method of Three Tables

  The next table is that of Deviation and Absence by Proximity, which includes things that are as close to the above phenomena as possible but which differ by not involving heat; so, for example, the full Moon, rock, air, water that is cold, and so on.   The third table is that of Degrees or Comparisons in which the phenomena in which heat features are quantified and ranked according to the amount of heat they involve. The Method of Three Tables

Having drawn up all these tables, the final stage of Bacon’s method is the Induction itself. This involves studying all the information displayed in the tables and finding something that is present in all instances of the phenomenon in question, and absent when the phenomenon is absent, and furthermore, which increases and decreases in amount in proportion with the increases and decrease of the phenomenon. The thing that satisfies these conditions is to be found by elimination and not by merely guessing. The Method of Three Tables

Problems  Induction is essentially a way of knowing future from past. All reasoning that goes beyond past and present experiences is based on cause and effect.  But how do we know the effect will follow the cause in future?  An inductive argument could always be false no matter how many observations we have made! David Hume

 Horn 1: There can be no inductive justification of induction because such justifications presuppose that some inductions are justified.  Horn 2: There can be no deductive justification of induction because deductive inferences are non-ampliative, but inductive inferences are ampliative. Problems

 Have you any solution?  Some attempt: Solution 1—the “success of science” solution: The reason we are justified in using inductive methods is that they work. Science, which utilizes such methods, has been massively successful in predicting the course of the future and providing us with an understanding of the natural world. To doubt its methodology is ridiculously irrational. Problems

Solution 2—Nature is uniform. Solution 3—The hypothetico-deductive Solution 4: The probability solution: Inductive inferences don’t, and aren’t meant, to generate certain conclusions. The best we can hope for using induction is conclusions that are probable. Problems

Other Problems Nelson GoodmanKarl Popper Grue Paradox Carl Hempel Raven ParadoxProblem of Infinity